Self-centering punch.



G. 1. MILLER.

LF CENTERING PUNCH.

9' me. Patented May 8, 1917.

2 SHEETS-SHEET l.

G. 1. MILLER.

SELF CENTERING PUNCH.

APPLICATION FILED MAY 19. 191s.

2 SHEETS-SHEET 2.

' Patented May 8, 1917.

i Il.

SELF-CENTERING PUNCH.

Specification of Letters Patent.

Patented May 8, 1917.

Application led'ay 19, 1916. Serial No. 98,634.

To all whom it may concern.'

Be it known that I, GEORGE J. MILLER, acitizen of the United States,residing at Winnebago, in the county of Faribault, State of Minnesota,have invented certain new and useful Improvements in Self-CenteringPunches; and I do hereby declare the following to be a full, clear, andexact description of the invention, such as will enable others skilledin the art to which it appertains to make and use the same.

This invention relates to punch markers, and has for its primary objectto provide a simple and improved device for transferring the centers ordimensions of apertures in one piece of material upon others in suchmanner that such apertures or openings may be exactly duplicated orreproduced in the article or material operated upon.

A further object of the invention is to provide a device of thischaracter which automatically centers itself, and whereby the use of thesame will greatly facilitate the operation of correctly reproducing theapertures in one material upon that of another.

A still further object of the invention is I to provide a centeringpunch or marker of the 'character described which may with facility beused in ransferring apertures from a pattern sheet to the material to beoperated upon.

A still further object of the invention is to provide a centering toolof this character which is composed of such parts as to enable the sameto be readily turned upon a machine.

A still further object of the invention is to provide a device of thischaracter which is of extremely simple and inexpensive construction,which is so arranged and constructed as to automatically center itselfwhen positioned within an opening, which is composed of but few readilyassembled parts, all so arranged as to preclude wear, breakage, orderangement of the same, and which will prove thoroughly efhcient in theattainment of the ends for which it is designed.

With these objects in view, together with others which will appear asthe description proceeds, the invention resides in the novel combinationand arrangement of parts, all

as will be described more fully hereinafter, illustrated in the drawingsand particularly pointed out in the claims.

The invention will be best understood by reference to the accompanyingdrawings, wherein:

Figure 1, is a side elevation of a centering tool embodying myinvention,

Fig. 2, is a longitudinal sectional view taken through the improvedcentering tool and illustrating the same in use,

Figs. 3 and 4 are longitudinal sectional views taken through heads ofvarious sizes and shapes arranged for use in connection with the tool,

Fig. 5 is a side elevation, partly in section, of my invention in usewith an attachment,

Fig. 6 is a vertical section of the attachment, and,

Fig. 7 is a section on line 7-7 of Fig. 5.

In the preferred embodiment ofthe invention, use is made of a shank 5having a central longitudinally disposed bore 6, the said shank beingformed of metal and is of a size to ybe conveniently gripped or held bythe hand. The inner walls of the shank adjacent the opposite endsthereof are threaded as at 7 and 8, the threads 7 being adapted to beengaged by threads formed upon the exterior of a boss 9 projectingrearwardly from a centering head 10. The threads S receive threads upona boss 11 formed upon a cap member 12, the said head and cap memberbeing provided with openings 13 and 14 respectively, the said openingsextending entirely through the head and cap member and communicating attheir ends with the bore 6 of the shank. A punch member 15 is arrangedwithin the shank for sliding movement longitudinally thereof, the saidpunch being of a size to slide within the openings 13 and 14 of the headand cap member, and is pointed as at 16 at its cutting end as shown. Thepunch member is held within the shank with its cutting end normallyretracted or inclosed by the head 10, an expansion spring 17 being usedto accomplish this end. This spring encircles the punch tang, and restsat one end against the boss 9 of the head, and at its opposite end upona collar 18 forming a shoulder sev cured to the punch tang. This collaris positioned upon the punch in such manner as to form a stop to limittheretracting movement of the punch member, the said collar engagingwith the boss 11 upon the cap member 12 when the said punch stem isretracted. It will be observed that when retracted, the rear end of thepunch tang protrudes from the cap member, and upon force being appliedto the said protruding end, the sharpened end 16 of the punch will becaused to project from the head 10.

The head shown in Figs. 1 and 2 of the drawings is of substantially coneshape, the opening 13 therein communicating at one end with the apex ofthe cone7 and at its opposite end with the central portion of the basethereof. It will be observed that upon insertion of the cone shape headwithin an opening, the inclined walls of the said head will cause theapex thereof to be disposed centrally of the opening, and operation ofthe punch will mark the exact center of the opening. Inl tracing orreproducing apertures of such large diameters as to preclude the propercentering of the cone shaped head therein, heads such as are shown inFigs. 3 and l of the drawing may be employed. These heads are providedwith the exteriorly threaded bosses 9 for engagement within the shankends, and may vary in diameter and construction at their point ofengagement within the apertures. The head shown in Fig. 3 of thedrawings is of substantially frusto-conical shape, and it is obviousthat relatively large apertures, or

apertures in relatively thin material, may be properly centered by theuse of this head. The head shown in Fig. 4t of the drawings presents atits outer extremity a flange 19, the edges of which are beveled as at20, the said head being adapted particularly for use in centeringapertures arranged in thin material.

By the construction set forth it is apparent that an extremely simpleand inexpensive tool is provided, and one of such construction as willbe capable of accomplishing its ends in an extremely simple manner. Thevarious heads are all l rovided with exteriorly threaded bosses o thesame dimensions, whereby the said heads are readily interchangeable, andwhen arranged on the shank will be rigidly held thereby. The exterior ofthe shank may be ribbed or milled as shown to enable the same to besecurely gripped and held by the hand.

In Figs. 5, G and 7 I have shown a device which is to be used inconnection with my invention for insuring an absolutely accuratecentering of the punch. A cylinder 21 has its interior cut out toclosely, but slidably lit the shank of the punch, so that the latter maybe vertically moved therein. The cylinder 21 is provided with legs 22,preferably three in number, which support the cylinder above the surface23 of the material which is being used as a pattern. In using theattachment, the shank is shoved into the cylinder 21 from the bottom,and the legs 22 then placed on the surface 23 with the head 10 in thepattern opening. Since the shank 5 fits the cylinder 21 snugly, the head10 cannot be canted to one side, when its point is inserted in thepattern opening, so that the member 15 must stand absolutely verticaland can only hit an accurate and true center.

Vhile I have herein shown and described a particular or preferredembodiment of the invention, I wish it to be understood that I need notconfine myself to all the precise details of construction herein setforth by Way of illustration as modication and variation may be madewithout departing from the spirit of the invention or exceeding thescope of the claims.

vWhat is claimed is:

1. In a centering punch, a hollow shank, threads at the ends of saidshank, a cap engaged with the threads at one end of said shank, and ahead engaged with thethreads at the opposite end of said shank, the saidhead and cap being provided with openings communicating with theinterior of said shank, a punch slidably arranged within said shank andadapted to have its sharpened end projected from said head the stem ofthe punch extending above the cap in all positions of the punch, acollar on said punch, and a spring within said shank engaged with saidcollar for normally holding said punch retracted, substantially asdescribed.

2. In a centering punch, a hollow shank having threads upon its interiorwalls at the erfds thereof, a cap of substantially the same diameter assaid shank, a boss projecting from said cap and having exterior threadsfor engagement with the threads at one end of said shank, the said capbeing provided with an opening communicating with the interior of saidshank, a head, a boss projecting from said head and having exteriorthreads thereon for engagement with the threads at the opposite end ofsaid shank, the said head having inclined exterior walls, and the headbeing provided with an aperture communicating with the interior of saidshank, a drill extending through said shank and resting in the openingsin said head and cap, a collar on said drill and a coil springinterposed between said boss and said collar for holding the latter`engaged with the cap boss and with one end of said drill projecting atall times beyond said cap, substantiallyas described.

3. In a centering punch, a shank having a tapered head at one endadapted to seat in a circular cavity, and having a central for slidablyreceiving the shank and a, plu- 10 rality of legs carrying saidcylinder.

ln testimony whereof, I aHiX my signature, in the presence of tWoWitnesses.

GEORGE JHN LER.

Witnesses:

E. C. GULBRoNsoN, G. A. BAssE'r'r.

